Geothermal energy system and method

ABSTRACT

A geothermal energy transfer and utilization system makes use of thermal energy stored in hot solute-bearing well water to generate super-heated steam from an injected flow of clean water; the super-heated steam is then used for operating a turbinedriven pump at the well bottom for pumping the hot solute-bearing water at high pressure and in liquid state to the earth&#39;&#39;s surface, where it is used by transfer of its heat to a closedloop boiler-turbine-alternator combination for the generation of electrical or other power. Cooled, clean water is regenerated by the surface-located system for re-injection into the deep well and residual concentrated solute-bearing water is pumped back into the earth.

United States Patent [1 1 [111 3,898,020

Matthews Aug. 5, 1975 GEOTHERMAL ENERGY SYSTEM AND METHOD PrimaryE.ranu'ner-Martin P. Schwadron Assistant Etamtner-Allen M. Ostrager [75]lnvemor' Hugh Matthews Acton Mdss' Attorney, Agent. or Firm-Howard P.Terry [73] Assignee: Sperry Rand Corporation, New

York, NY. [57] ABSTRACT [22] Fil d; May 8,1974 A geothermal energytransfer and utilization system makes use of thermal energy stored inhot solute- [211 Appl' 468l30 bearing well water to generatesuper-heated steam Related US, A li ati D t from an injected flow ofclean water; the super-heated steam is then used for operating aturbine-driven [62] Division of Ser, No, 300,058 Oct. 24, 1972, Pat. No.

pump at the well bottom for pumping the hot solutebearing water at highpressure and in liquid state to 52 us 3 17 379; 41 the earths surface,where it is used by transfer of its IL CL 120 17 00; o 00; F03g 7 00heat to a closed-loop boiler-turbine-alternator combi- 3 Field f Search60/641 645, 651 70 nation for the generation of electrical or otherpower.

60/671; 417/379v 405 406, g Cooled, clean water is regenerated by thesurfacelocated system for re-injection into the deep well and [56]References cu residual concentrated solute-bearing water is pumpedUNITED STATES PATENTS back 3,751.673 8/1973 Sprankle t. /64l x 8 Claims.3 ng Figures E I gws [v g 6 1' j g I i s 3 a s 41 4 4 h L 39 29 39 T 3 iI, 40 a Q Q I 27 23 2a 17 I" I 2 1s 19 21 l' as Q t 'l 29 I 2 H 22 I 24Q 39 l I 26 Q Q a I Q 34 I41 I l l 53 r I 25- H I I 31 a e H w 46 s i tt. W s i l l I 1111 is g g I: Q 35 3 8 S r q/\/\ LM I \36 PATENTEUAUB5191s :1 898, 020

GEOTHERMAL ENERGY SYSTEM AND METHOD CROSS REFERENCE TO RELATEDAPPLICATION This is a division of patent application Ser. No. 300,058,filed Oct. 24, I972, now US. Pat. No. 3,824,793 and entitled GeothermalEnergy System and Method" in the name of Hugh B. Matthews.

BACKGROUND OF THE INVENTION 1. Field of the Invention The inventionrelates generally to efficient means for the generation of electrical orother power utilizing energy from geothermal sources and, moreparticularly relates to arrangements including efficient superheatedsteam generation and pumping equipment for application in deep hot waterwells for transfer of thermal energy to the earth's surface.

2. Description of the Prior Art While geothermal energy sources havebeen employed for the generation of power to a limited extent, availablesystems operate at relatively low efficiency and have many additionalserious disadvantages. In the relatively few installations in whichsubstantially dry steam is supplied by wells at the earths surface, thesteam may be fed, after removal of solid matter, from the well headdirectly to a turbine. On the other hand, most geothermal wells arecharacterized by yields of a mixture of steam and hot water at theearths surface so that the water must be separated from the steam beforethe latter is used in a turbine.

In both of these kinds of installations, relatively low pressure steamnormally results, requiring special tur bines and yielding relativelyinefficient power generation as compared to generation of power usingnormally operated fossil fuel-powered or nucleanpowered electricalgeneration equipment. In only a few instances do geothermal wellsactually produce truly superheated steam with only minor amounts ofundesired gasses and with no liquid water.

The presence of significant amounts of liquid water in wells used withprior art geothermal systems presents other problems in addition to theseparation problem. If the water is only moderately hot, extractingthermal energy from it may be expensive or, at least, inefficient.Whether or not the heat is used, the water must be handled. The waterusually bears considerable concentrations of silica and of alkali salts,including chloride, sul fate, carbonate, borate, and the like ions, allof which dissolved salts present precipitation problems at the point atwhich any part of the water may abruptly turn to steam. If the alkalinewater is allowed to escape at the installation, severe stream or riverchemical and thermal pollution results. Finally, there is some evidencethat the removal of large amounts of water from geothermal reservoirsmay lead, in a generally unpredictable manner, to undesirable landsubsidence in the vicinity of thermal well installations.

SUMMARY OF THE INVENTION The present invention provides means forefficient power generation employing energy derived from geothermalsources through the generation of dry superheated steam and theconsequent operation of subsurface equipment for pumping extremely hotwell water at high pressures to the earths surface. Clean water isinjected at a first or surface station into the deep well where thermalenergy stored in hot solutebearing deep well water is used at a secondor deep well station to generate super-heated steam from the cleanwater. The resultant dry super-heated steam is used at the well bottomfor operating a turbine-driven pump for pumping the hot solute-bearingwell water to the first station at the earth's surface, the water beingpumped at all times and locations in the system at pressures whichprevent flash steam formation. The highly energetic water is used at thesurface or first station in a binary fluid system so that its thermalenergy is transferred to a closed-loop surface-located boiler-turbinesystem for driving an electrical power alternator. Cooled, clean wateris regenerated by the surface system for re-injection into the well foroperation of the steam turbine therein. Undesired solutes are pumpedback into the earth via a separate well in the form of a concentratedbrine.

In contrast with the relatively poor performance of prior art systems,the present invention is characterized by high efficiency as well as bymany other advantageous features, it is not limited to use with the raredry steam sources, and it is devoid of the water and steam separationproblems attached to the more usual prior art systems used with mixedsteam and hot water supply wells. Since the novel power system operateswith dry, highly super-heated steam, existing efficient heat transferelements and efficient high pressure turbines may readily be employed.According to the invention, the very large calorific content of hightemperature water subjected to high pressure is efficiently employed.Since high pressure liquid is used as the thermal transfer medium.undesired flash steam formation is prevented, along with its undesiredattendant deposition of dissolved materials. Since the dissolved saltsare efficiently pumped back deep into the earth as remotely as need befrom the geothermal source, surface pollution effects are avoided andthere is relatively little risk of land sinkage in the vicinity of thegeothermal source.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation view, mostly incross section, of the novel deep well geothermal pumping apparatus ofthe system.

FIG. 2 is a diagrammatic representation of the apparatus of the earthssurface cooperating with the pumping apparatus of FIG. I.

FIG. 3 is an elevation view in cross section of a part of the apparatusof FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention provides anefficient mechanism for extracting geothermal energy for the generationof electrical or other power from heat which naturally radiatesoutwardly toward the surface of the earth from its interior andespecially from hot strata providing localized geothermal energy sourcesfound in many localities in the very outer layers of the earths surface.In these thermal reservoirs, thermal energy is stored both in solidearth materials of the strata and in water and in steam, since waterreadily migrates into hot fractured rock beds and cavities therein, thewater and steam being capable of transferring heat energy from suchthermal reservoirs to a water or steam well and thence to the earthssurface. Water or steam may also serve as media for transferring heatfrom a deeply located geothermal source, the water flowing upwardly todepths which may readily be reached by drilled wells.

FIGS. 1 and 2 illustrate the structure of the portion 1 of the novelgeothermal energy system which is immersed in a deep well in strata farbelow the surface of the earth or other planet and which is locatedparticularly at a depth such that a copious supply of extremely hotwater under high pressure is naturally available, the structure beingsupported at the second station within a generally conventional wellcasing pipe or conduit 2. Extending downward from the well head 3 (seenin FIG. 2 and located at or near the earth's surface), the casing pipe 2surrounds in preferably concentric rela tion an innermost stainlesssteel or other quality alloy steep pipe or conduit 4 for supplyingrelatively cool and relatively pure water near the bottom of the wellfor purposes which will be explained. A second larger internal diameterpipe or conduit 5 of similar quality and surrounding pipe 4 is alsoprovided within casing 2, extending from well head 3 to the energysystem apparatus at the bottom of the well for permitting the hotturbine exhaust steam to flow to the surface of the earth, as will bedescribed.

The novel geothermal energy extraction apparatus 1 located at the bottomof the well comprises, as will be explained, several cooperatingelements, including a steam generation section 6, a steam turbine orother ro tary motive section 7, and a rotary hot water pumping section 8driven from motive section 7. The several ele ments of the threesections are suspended in cooperative relation adjacent the bottom ofthe well within casing 2 and relative to the inner pipes 4 and 5,partial support being supplied at seal 9 from the inner wall of casingpipe 2 and further support by concentric pipes 4 and 5. Additionalsupport or alignment means may be supplied, as will be evident to thoseskilled in the art, by additional support elements which may be of con'ventional nature.

It will be seen in FIG. 1 that relatively clean and cold water is pumpeddown inner pipe 4 from the first or surface station to the region ofconstriction 10. On the upper side of constriction 10, one or moreopenings are formed in pipe 4, such as opening 11, coupling cool waterthrough branching pipe 12 to a conventional pressure regulator andreducer l3. Openings ll, pressure regulator and reducer l3, and theactual pressure of the clean water present in pipe 4 are arranged topermit clean water to flow through pipe 14 into the steam generationsection 6 without undesired back-flow of steam. The clean water flowsfrom the conventional pressure reducer and regulator 13 located betweenpipes 4 and 5, through pipe 14 and into a long alloy steel heatexchanger or boiler tube 15 formed as a plurality of turns which may belocated in a cylindrical stack between pipe 5 and easing pipe 2.

Extremely hot water flows upward in the region between pipes 2 and 5, aswill be seen, for converting the clean water injected into coiled tube15 into highly energetic dry super-heated steam. The clean water, beforeflowing through pressure regulator and reducer 13, is at a very highpressure due to its hydrostatic head. Pressure reducer 13 drops thispressure sufficiently so that the clean water can be vaporized andsuper-heated by the well water. The resultant steam is directed througha downwardly oriented pipe 16 extending from the last turn 17 of coiledpipe 15 of steam generator section 6, pipe 16 lying adjacent the innerwall of casing pipe 2. In the vicinity of the last turn 17 of steamgenerator section 6 and of the downwardly extending pipe 16, the pipe 5is expanded in diameter so as to form an expanded section 18 generallycommensurate in cross section with the shape of steam turbine 19.

Steam turbine 19 is supported within the confines of an oppositelytapered alloy steel cylindrical wall 20, which wall serves as anextension of the expanded wall section 18, and the opposed spacedparallel circular steel walls 21 and 22. Turbine 19 is supplied withwater-lubricated bearing housings 23 and 24 located at the centers ofthe respective circular walls 23, 24. Bearing housings 21, 22respectively contain bearings for direct support of the main shaft 25 ofturbine 19, as will be further explained. Walls 20, 21 and 22 aresolidly bonded together as by welding or other fastening means forserving as a supporting enclosure of turbine 19', however, the highpressure steam pipe 16 is permitted entry into the input section ofturbine 19 through aperture 26 in bottom wall 22. Likewise, an array oflarge openings, such as apertures 27 and 28, are provided in the uppercircular wall 21 so as to permit exhaust of used steam from turbine 19into the space between concentric pipes 4 and 5. Thus, relatively cleanwater flowing downwardly in the sense of arrow 29 within pipe 4 may flowafter conversion as partially spent dry steam upward to the well top inthe sense of arrows 30 in the region bounded by pipes 4 and 5.

Steam turbine 19 may be selected from several types of availabledevices; for example, turbine 19 may be of the type commonly defined asthe impulse turbine, wherein steam expansion occurs only in thestationary blades or nozzles of the turbine. In such devices, theturbine may consist of a nozzle followed by a plurality of rows ofblades rotating about an axis, the blades being separated by redirectingblades. Suitable turbines, are described, for example, on page 1,225 etseq. of L. S. Marks: Mechanical Engineers Handbook, Fourth Edition(1941), McGraw-Hill Book Company, Inc., and elsewhere.

The steam generation section 6 and the turbine 19 may be one of theconventional arrangements of the type using steam generating coils inseries or in parallel relation or may include one or more separatestacked coils in section 6 for reheat of steam between stages of turbine19. In some applications, at least a two stage turbine will be usedaccording to the permitted outer diameter of the turbine.

The function of steam turbine 19 is to drive the hot water pump 31located within pumping section 8. Several types of rotary multiplestage, mixed-flow, or turbo-pumps equipped with vane diffusers areavailable for use as pump 31, including certain types of pumps oftenused as deep well pumps. Pumps of suitable kind are described liberallyin the literature. For example, reference may be had to page 5-59 etseq. of .I. K. Salisbury: Kems Mechanical Engineers Handbook Power, l2thEdition (l954), John Wiley and Sons.

Pump 31 is supported within a cylindrical housing 32 concentricallylocated within casing pipe 2. The upper portion of housing 32 issmoothly expanded in diameter to form a tapered well section 33 having ashaped upper part suitable for sealing at 9 to the inner wall of casingpipe 2. The tapered wall 20 surrounding turbine 19 is extended to formbell shaped section 34, tapered wall 33 and bell-shaped wall 34 beinggenerally similar in curvature so as to form an annular hydrodynamicfluid flow region between them, as will be ex lained.

Pump 31 is retained in part within housing 32 by a steel end wall 35,welded or otherwise fastened to housing 32 at annular surface 36. Wall35, at its center, accommodates an end thrust bearing housing 46 forsupporting the end 37 of shaft 25; it will be seen that bearing housings24 and 36 contain bearings which may be clean water lubricated and whichmay cooperate in supporting shaft 25 and the impeller of hot water pump31. End wall 35 has an annular array of apertures, such as opening 38,which admit hot water to pump 31; the latter fluid is accelerated by theimpeller of pump 31 and exits therefrom into the annular region definedby the respective concentric tapered and bell shaped walls 33, 34. Sincethese sections are respectively and smoothly joined to casing pipe 2 andto pipe 5, the hot water is pumped upward to the top of the well in thesense of arrows 39.

It is observed that the size of openings 11, the characteristics ofpressure regulator 13, and the pressure applied to the cool water at thetop of the well are adjusted appropriately for the supply ofbearinglubricating water through constriction downwardly through pipe 4to bearing housings 23, 24 and 36. In the several bearings, thelubricating water is forced between bearing surfaces, maintaining theirseparation in the conventional manner while serving as a lubricant.Having served these purposes, the used water is permitted to exit fromthe respective bearing housings, as via the respective orifices 40, 41,and 42 of the housings 23, 24 and 36. The bearing lubricating waterleaving orifice 40 in bearing housing 23 has sufficient pressure, forexample, to flow into the exhausting steam from turbine 19; being ofsmall volume, it has insignificant effect. From orifice 41 in bearinghousing 24, the lubricating water simply flows into the rising hot waterstream indicated by arrow 39. The lower bearing housing 36 and thebearing it contains are lubricated by water that afterwards exitsorifice 42 into the hot water being pumped by pump 31. In each case, itis seen that the pressure of the clean lubricating water is such as toprevent undesired reverse flow. For example, at orifice 42, the cleanwater pressure is sufficient to prevent contaminated well water fromentering housing 36 and destroying the bearing therewithin. Since theoperation of turbine 19 and pump 31 may in practice either tend to liftor to lower the shaft 25 common to them, the bearings within housings 23and 36 necessarily have both alignment and thrust absorbing functions.As is well known by those skilled in the art, such bearings may bedesigned to operate to maintain the fluid gap in a substantiallybalanced hydrostatic thrust condition.

As shown in FIG. 2, the objective of the deep well apparatus of FIG. 1is to generate large quantities of electric power at the first orsurface station using vapor turbines and electrical generatorspreferably located at ground level, such as vapor turbine 60 and theelectrical alternator 61 of FIG. 2, at power output terminals 62. Forthis purpose, the hot water pumped to the earth's surface is fed by pipe5 and its extension (pipe 63) through the normally open valve 64 toelement 66 of the conventional boiler'heat exchanger device 65. Device65 is of conventional closed tank-like nature and is designed toexchange heat between the several heat exchanger elements 66, 70, 71, 72contained therein. The elements 66, 70, 71 and 72 may take the form oflineal or coiled pipes exchanging heat energy by direct conductionthrough their metal walls or through a suitable interposed fluid in thewell known manner. Heat from the hot water of pipe 63 is a major sourceof heat for supply to device 65. The hot water, having been relativelydropped in temperature within boiler-heat exchanger 65, is then fed viapipe 67 through the normally open valve 68 to the conventionalevaporator 69. Valve 68 may be a throttle valve adjusted for the purposeof dropping the pressure of the fluid flowing through it so that thefluid will readily flash at low temperatures when supplied to evaporator69.

Evaporator 69 is of conventional nature and is supplied in the usualmanner with a conventional vacuum pump 70 which considerably reducespressure within evaporator 69, causing the water therein to boil, andreleasing steam via exhaust 71. Vacuum pump 70 serves to remove the mostvolatile gasses at terminal 72, some of which gasses are undesirable,being corro sive, from circulation past evaporator 69 into condenser 73.Valuable gasses, such as helium and other noble gasses, may be extractedat terminal 72 and utilized, if desired.

Evaporator 69 performs two functions; as suggested in the foregoingparagraph, it generates clean steam which is condensed by theconventional condenser 73 and is supplied as water at junction 74 foraugmenting the clean water supply. A further major portion of the wateroriginally flowing upward in pipe 5 is returned by pipe 75 through pump76 to the earth well formed by pipe 77. Thus, a major portion ofdissolved mineral salts pumped to the surface in solution in the hotwater in pipe 5 is returned by pump 77 into the ground. The well formedby pipe 77 may be reasonably remote from the well of the thermal system1 and may serve more than one such system. It may pass the liquid frompump 76 into an earth stratum different from that associated with theportion 1 of the system, if desired.

A second source of energy supplied to boiler-heat exchanger device 65 isthe steam exhausted from the deep well turbine 19 (FIG. 1) via pipe 5.This steam is permitted to flow through normally open valve 78 to theheat exchanger element 70 of boiler-heat exchanger device 65. Element 70is arranged so that the steam therein is exposed to thermal interchangeat the coolest end of device 65 (adjacent the cool clean water input toheat exchanger element 71). Accordingly, the exhaust steam from pipe 5is largely condensed within heat exchanger element 70. The water thuscondensed is supplied through pipe 79 and the normally open valve 80 tothe aforementioned junction 74. The water from pipe 79 and that fromcondenser 73 arrives at junction 74 in relatively pure state and maytherefore by supplied to the cold water input pipe 4 of the apparatus ofFIG. 1. With valve 81 in branch line 82 closed, the water at junction 74is fed by a conventional feed pump 83 through the normally open valve 84and pipe 85 into pipe 4. It will be appreciated that a variable capacitystorage tank may be inserted at the general location of junction 74, sothat any fluctuations in supply of clean water for injection by pipe 4may be smoothed. Also, such water may be supplied by opening the valve81 from any available source coupled at terminal 91. It will further beunderstood that condenser 73 may be water cooled, as by supply of coolwater from a cooling tower (not shown) to heat exchanger element 86 inheat exchanger 73. Alternatively. element 87 may be cooled in manylocations simply by forced air.

The major elements for supply of heat into boilerheat exchanger device65 have now been described. The heat stored therein is removed and usedin a substantially conventional manner to operate the surfacelocatedvapor turbine 60. For this purpose, liquid is supplied by a conventionalfeed pump 88 via pipe 89 to the heat exchanger element 71 of boiler-heatexchanger 65. Flow of the liquid is counter to the direction of flow ofheat into device 65 in elements 66, 70, and 72. The liquid evaporatesand consequently generates extremely high temperature vapor that iscoupled via pipe 90 to the input stage of turbine 60. After performinguseful work therein, the turbine exhaust vapor is fed by pipe 91 intoboiler-heat exchanger 65, where part of its remaining thermal energy isabstracted near the input of element 7]. The vapor then flows to aconventional condenser device 93 having heat exchanger elements 92 and94 and then flows again as a liquid via pipe 96 to the feed pump 88.Condenser 93 may be cooled by flow of water from a cooling tower (notshown) through heat exchanger element 94. The ex changer 93 mayalternatively be air cooled in the conventional manner. A fluid such aswater may be used for the generation of high temperature vapor withinboiler-heat exchanger 65 and its associated surfacelocated loop orcertain organic fluids affording best use in Rankine cycle operation mayalternatively be employed.

Operation of the invention will be apparent from the foregoingdescription. It is seen that the geothermal energy deep well system 1consists of a deeply submerged super-heated steam generation section 6,a turbine section 7 driven by the superheated steam, and a hot waterpumping section 8 all located in a source region where there is presentlarge quantities of extremely hot water which may also includerelatively large quantities of dissolved materials. Clean water, formedby condensing the clean steam at the surface, is supplied to the steamgeneration section 6 for driving the turbine 19 and is also supplied tohearings in the turbine and pump sections thereof. The pump section 8serves to increase the pressure level of the hot water so that itreaches the surface of the earth still well above its saturationpressure.

The pressure head in the vicinity of pump 31 is great enough to preventcavitation damage to the pump and any consequent performance loss in thepump. in general, it is arranged that actual pressures in the hot waterare maintained above the flash point by a wide safety margin at allpoints within the hot water flow system within the well. This feature isone of particular importance for the success of the invention. since thehot water cannot flash into steam when held at all times and locationsabove its flash pressure. Flashing of the hot water into steam is to beprevented, since it is likely to be disruptive if not actuallydestructive of equipment and at least will result in the deposition oflarge amounts of mineral scale in the general location of the flashevent. The system at the surface of the earth may then readily extractheat from the extremely hot water for the generation of electrical poweror for other useful purposes. What energy remains in the steam used todrive the deep well turbine section 7 is also returned to earth'ssurface for recovery in the surface-located system.

The deep well portion 1 may be started or stopped in the followingmanner. For example. with no power supplied to pump 88 and with valve 84closed and valve 81 open, conventional sources of high pressure cleanwater and compressed air at terminal 91 may be used to force air andwater down pipe 4 into the steam generation section 6 and into bearinghousings 23, 24, 36 to lift the bearings. Turbine 19 begins to turn,first as a result of the compressed air flow, then as a result of steambeing generated, gradually increasing its speed, pump 31 graduallylifting more and more hot water through pipe 5. The ratio of air towater is reduced until purely water is supplied, which supply may thenbe switched to pump 83 by closing valve 81 at the same time valve 84 isopened. This operation continues until the first steady state of theloop containing geothermal apparatus 1 is reached, boiler-heat exchanger65 having substantially reached operating temperature. Now, pump 88 isstarted and high energy steam begins to be supplied by pipe 90 to thesurface-located turbine 60. Eventually, this second loop reaches itsfirst steady state condition, after which the useful load may be placedacross alternator 61. The entire system shortly reaches a finalequilibrium status with respect to the load on alternator 61, supplyinguseful electrical power in large amounts, regenerating clean water forits own use within the deep well apparatus 1, and returning undesiredsolute-containing material to the earth's interior via the well of pipe77. The system may be shut down by closing valves 64 and 78 and bygradually cutting off the supply of cold water flowing through pipe 85.

It will be understood that techniques well known in the art may be usedto extract even more energy from the system at the first station when inoperation. For example, the energy of the hot water flowing in pipe 67out of heat exchanger element 66 may be used in part by supplying it toa conventional liquid turbine (not shown) that may be used mechanicallyto drive various pumps, such as pumps and 76, and other pumps that maybe required in the usual manner in pipes coupled between heat exchangers73 and 93 and any associated cooling towers. On the other hand,electrical power from alternator 62 or from a standby start-up generatormay be supplied to the respective terminals 100, 101, I02, and 103 ofpumps 88, 70, 76, and 83 to electrical motors integrated within each ofthe several pumps.

The bearings contained within bearing housings 23, 24, and 36 maygenerally be of well known types, including types used in conventionalturbines and do not require detailed discussion. Since the direction ofthrust on the bearings when the machine of FIG. 1 is operating is wellknown to those skilled in the art to be controllable in a conventionalmanner by the designer, the major thrust may be placed in an upwarddirection along shaft 25, an aid to the support of the mass of the shaftand of the turbine and pump rotors. Fluid film bearings of the typeusing a large flow of liquid are suitable. They may use faces definingthe fluid bearing gap composed of rubber, as in conventional deep wellpumps, or of refractory materials such as certain ceramics. Dialuminatrioxide (A1 0 has been found useful as a material in such bearing faceswhen coated on an alloy steel backing surface. Other suitable bearingfaces are readily available.

A generally conventional fluid bearing useful in the invention isillustrated in one form in FIG. 3 as it might be applied within theturbine bearing housing 23, for example. As is also seen in FIG. I,downward flowing lubricating water is supplied in pipe 4 to the bearinghousing 23 which is affixed to a stub pipe 110 integral with andextending upwardly from the upper wall 21 that encloses turbine 19 (notshown in FIG. 3). The stub pipe 110 has a relatively large vertical borefor accommodating the rotor 111 of the aligning portion of the bearing,a gap 112 being provided between the outer cylindrical surface 113 ofbearing rotor 111 and the inner cylindrical surface I14 of stub pipe110. The aligning bearing rotor 111 is affixed within a short bore at115 at the upper end (for example) of shaft 25, shaft 25 being suppliedwith an internal bore 116 coupling lubricating water from pipe 4 towardany lowermounted bearings.

The end of shaft 25 is provided with a circular thrust bearing rotor H7which, if desired, may be intergral with shaft 25. In normal operation,a gap 118 is formed between opposed surfaces of thrust bearing rotor 117and a bearing face 119, such as a bearing face formed on a surface ofwall 21. Flow of fluid outward to aperture 40 is controlled in part bythe operating widths of gaps 112, 118 and the relative diameters of pipe4, of the bore in rotor 111, and of the bore H6 in shaft 25. Propermetering may be aided by the meter orifices in inserts 115 through whichwater is injected into gap 1 18.

While the invention has been described in its preferred embodiment, itis to be understood that the words which have been used are words ofdescription rather than of limitation and that changes within thepurview of the appended claims may be made without departure from thetrue scope and spirit of the invention in its broader aspects.

l claim:

1. Apparatus for transferring thermal energy from an interior hotstratum of an earth for utilization adjacent the surface of said earthcomprising:

first, second and third conduit means,

rotary pump means operatively coupled for pumping hot liquid within saidfirst conduit means,

rotary motive means for driving said pump means operatively coupledwithin said second conduit means, and

heat exchanger means within said first conduit means having liquid inputmeans operatively coupled to said third conduit means and output meansfor suppling hot driving vapor to said rotary motive means.

2. Apparatus as described in claim 1 wherein said rotary pump meanscomprises rotary multiple stage liquid pump means.

3. Apparatus as described in claim 2 wherein said ro tary motive meanscomprises rotary impulse vapor turbine means.

4. Apparatus as described in claim 3 wherein said r0 tary pump androtary motive means have common driving shaft means equipped with liquidlubricated bearing means.

5. Apparatus as described in claim 4 wherein said common shaft meansincludes an axial bore,

6. Apparatus as described in claim 5 wherein said axial bore within saidcommon shaft means is coupled to said third conduit means for supply ofliquid lubricant to said bearing means.

7. Apparatus as described in claim 1 wherein said first, second, andthird conduit means comprise substantially concentric pipe means.

8. Apparatus as described in claim 6 wherein said third conduit meansand said common shaft means are adapted for use with pump means forproviding fluid flow only from said third conduit means through saidcommon shaft means and then through said liquid lubricated bearingmeans.

1. Apparatus for transferring thermal energy from an interior hotstratum of an earth for utilization adjacent the surface of said earthcomprising: first, second and third conduit means, rotary pump meansoperatively coupled for pumping hot liquid within said first conduitmeans, rotary motive means for driving said pump means operativelycoupled within said second conduit means, and heat exchanger meanswithin said first conduit means having liquid input means operativelycoupled to said third conduit means and output means for suppling hotdriving vapor to said rotary motive means.
 2. Apparatus as described inclaim 1 wherein said rotary pump means comprises rotary multiple stageliquid pump means.
 3. Apparatus as described in claim 2 wherein saidrotary motive means comprises rotary impulse vapor turbine means. 4.Apparatus as described in claim 3 wherein said rotary pump and rotarymotive means have common driving shaft means equipped with liquidlubricated bearing means.
 5. Apparatus as described in claim 4 whereinsaid common shaft means includes an axial bore.
 6. Apparatus asdescribed in claim 5 wherein said axial bore withIn said common shaftmeans is coupled to said third conduit means for supply of liquidlubricant to said bearing means.
 7. Apparatus as described in claim 1wherein said first, second, and third conduit means comprisesubstantially concentric pipe means.
 8. Apparatus as described in claim6 wherein said third conduit means and said common shaft means areadapted for use with pump means for providing fluid flow only from saidthird conduit means through said common shaft means and then throughsaid liquid lubricated bearing means.